The present invention relates to annular friction rings or discs which are conventionally utilized in wet clutch packs of interleaved clutch plates that are alternately connected to an inner hub and an outer drum of a clutch assembly and are engaged to rotate the parts together by a hydraulically or spring-actuated piston. A friction disc or plate normally consists of an annular steel ring or plate, which serves as a core plate, and a pair of annular friction facings that are riveted or otherwise secured to the core plate to complete the friction disc.
Blanking out the friction rings and annular core plate produces considerable offal which averages to approximately two-thirds of the total material used. This results in a considerable problem of recycling material, and certain friction materials cannot be recycled which is particularly wasteful and expensive.
To overcome the problem of offal in the blanking out of the annular friction facings, the U.S. Pat. No. 4,260,047 to Nels advanced the concept of an annular core plate and segmented friction facings having tab and slot interlocking ends. The friction facings consist of quarter circle segments which are blanked out of a rectangular sheet of friction material that is formed with a plurality of parallel grooves, with the tabs and slots formed in ungrooved portions. The segments are interconnected to form a ring and are bonded to the core plate. Although waste friction material is reduced, the grooving process and the waste of steel in blanking out the core plate remains. The present invention improves on the process of the Nels patent.